In present designs a large external decoupling capacitor is needed at the output of an LDO for increasing the separation between the pole at the output and pole at gate of a pass device under low to medium range of load current.
A larger capacitor requires a larger footprint on the printed circuit board (PCB) real estate which is very expensive for handheld applications.
Larger external decoupling capacitors would result in longer time to charge and discharge. If the LDO/Amplifier is regularly enabled or disabled it would add to loss in charge of battery.
Disadvantages of present designs are:                Limited stability        Output capacitor size        Large output impedance for driver stage        Too high gain        Too much time required to charge and discharge the LDO        Too much charge required for startup        Too much charge lost when LDO is disabled        Too high system boot-up time when LDO is used in a power management integrated circuit (PMIC) together with other LDOs        Too much time required for testing an IC hosting the LDO        
It is a challenge to designers of LDOs to improve stability of LDOs and to reduce the size of the output capacitor.